Farm equipment has evolved significantly over time to enable farmers to grow mass quantities of food while making efficient use of time and agricultural land. Centuries ago, farming was very labor intensive and families typically lived on small farms using domesticated animals and simple tools to prepare the land and plant crops. The long hours in the field during these times generally resulted in low product yields. Over time, horse powered farming equipment was replaced by steam powered tractors and ultimately by gasoline and diesel powered tractors, which are still primarily used today. Today, farming has advanced into an integrated system of specialized farming equipment, science, and computers, which has greatly reduced the amount of labor needed to produce large quantities of food and other crops on limited land area.
The marriage of farming and science has enabled farmers to vastly increase crop yields from fewer acres while reducing labor requirements. Pesticides, such as herbicides, insecticides, fungicides, rodentcides, and nematicides are used to control or destroy unwanted pests such as weeds, insects, disease, rodents, and nematodes that decrease crop yields. Pesticides are generally in a liquid, suspension, or solid form. The type of pesticide used and method of application can vary for any number of reasons, such as geography, the type of crop grown, time of application, and the pest to be controlled. For large-scale farming needs, pesticides that are in liquid form are commonly applied directly onto the cropland or crops by motorized sprayers mounted on or pulled by a tractor or an aircraft. Granular pesticides, on the other hand, are commonly delivered directly onto or into the soil to control pests living on or underneath the soil surface.
The proper application of pesticides is critical to ensuring optimum crop yields. Overapplication of pesticides is not only a financial loss, but also may result in adverse effects to the soil and surrounding ecology, and harm to the crops that farmers desire to protect. Similarly, under application may not sufficiently protect the crops from pests, resulting in reduced crop yield and sub-optimum land utilization. Accordingly, it is important that pesticides be applied using applicators capable of uniformly delivering the chemical at an accurate rate to insure that the optimum amount is released to the target area. Consequently, a variety of liquid and granular applicators, from large power driven equipment to hand-held equipment, have been designed for applying the pesticides to meet the needs of farmers.
At planting time, spreaders are commonly used for applying granular pesticides such as fungicides, herbicides and insecticides for large-scale farming needs. Generally, conventional planter-spreaders are comprised of a plurality of individual planter units each carrying a hopper having a chemical metering device for dispensing the granular pesticide. The pesticide granules are held in the hopper and flow by gravity into the chemical metering device and then are dispensed through an aperture in the meter.
There are a number of variables that affect the rate at which the granular pesticides are delivered to a target area. For example, the size of the meter aperture can significantly increase or decrease the delivery rate. The size that the meter aperture is set to is also dependent upon the size of the individual granules of the product. Also, the speed at which the spreader travels affects total output per unit area. When speed increases, less material is applied per unit area, and when speed is reduced, more material is applied.
Since each granular pesticide has unique flow characteristics, each chemical meter must be individually calibrated to ensure that the equipment uniformly applies the correct amount of the product. Calibration is simply determining the amount of material dispensed from the spreader over a known area at a known speed. In an effort to assist the proper calibration of the granular meters, pesticide manufacturers usually include charts or tables on the labels of their products that provide recommended meter settings for specific spreaders at various speeds. However, the manufacturer's recommended rates are based on new equipment and farmers strive to improve the accuracy of the application rates especially since granular pesticides are becoming more concentrated and expensive in recent years. Further, since granular products are abrasive, wear and tear on the equipment can be substantial, causing inaccurate delivery rate settings as equipment is repeatedly used over time.
For these reasons, then, many farmers use the recommended settings as a starting point and calibrate each individual meter through a common, time consuming trial and error method. This method typically involves filling the hoppers with a quantity of product, setting the meter aperture, and then using a collection device for collecting the product released over a select distance at a select speed. Thereafter, the product collected by the collection device is weighed and the amount converted to mass per acre basis to determine the actual rate of application. If the spreader applies too much product, the size of the meter aperture needs to be decreased, and if the spreader applies too little product, then the size of the meter aperture needs to be increased. There are several variations of this method that are known and used to calibrate granular dispensers.
The calibration methods used today are time consuming and can be an added farming expense especially if a professional is hired to perform the calibration. Moreover, these calibration methods need to be performed each season to account for wear and tear of the dispensers to ensure accuracy as well as each time a different chemical formulation or product is dispensed. Accordingly, there is a need for an improved method for calibrating these conventional devices that not only ensures accuracy and is also less time consuming, but also permits farmers with the flexibility of calibrating the dispensers for different granular products and differing application speeds. The present invention is directed to meeting these needs.